Claude Fable 5 is now available on Happycapy.

This is the first Mythos class Claude release, built for demanding work that needs long context, visual understanding, complex app building, and sustained execution.

We were excited to bring it into [Happycapy](https://happycapy.ai) because stronger models become much more useful when they are part of a real workflow. Instead of only answering in chat, Fable 5 can work inside a full sandbox environment where it can build, run, iterate, and deliver files.



Here are a few things we tried with Fable 5 on Happycapy:

1. A playable Three.js arena game

We asked it to build a 3D action game where capsule bots fight with glowing lightsabers while enemies shoot fireballs back.

What stood out was how complete the game felt. The controls, enemy behavior, damage system, health bars, camera movement, and combat feedback all worked together in a way that made the result feel playable, not just visually interesting.



2. A liquid glass interface from a background image

We gave it a background image and asked it to create a draggable liquid glass UI on top of it.

The result had floating cards, a travel dashboard, a map preview, a dock, and an assistant bubble with frosted blur, soft refraction, depth, highlights, and smooth drag behavior. It felt like a strong test of both visual understanding and frontend execution.

3. A NASA asteroid visualization

We asked it to build an interactive Three.js solar system using real NASA asteroid data.

This was a more complex task because the app needed to handle data fetching, rendering, filters, tooltips, scale controls, and a mission control style interface in one working experience.



The biggest thing we noticed across these examples was that Fable 5 handled multi part workflows really well. It was able to keep the visual direction, interaction logic, implementation details, and final output connected inside [Happycapy](https://happycapy.ai).

Claude Fable 5 is live now on Happycapy. Try it in your next workflow and let us know what you build with it.